Security personnel gather near the scene of an explosion outside the Urumqi South Railway Station in Urumqi in northwest China's Xinjiang Uygur Autonomous Region on Wednesday April 30, 2014. An explosion shook the railway station in China's restive far-western region of Xinjiang, injuring many people as President Xi Jinping wrapped up a four-day visit to the area, state media said Wednesday. (AP)

Security personnel gather near the scene of an explosion outside the Urumqi South Railway Station in Urumqi in northwest China's Xinjiang Uygur Autonomous Region on Wednesday April 30, 2014. An explosion shook the railway station in China's restive far-western region of Xinjiang, injuring many people as President Xi Jinping wrapped up a four-day visit to the area, state media said Wednesday.(AP)

Days after Chinese president Xi Jinping vowed to leave terrorists scurrying like rats, an explosion erupted at a train station in the country’s distant Xinjiang region, killing three and injuring at least 50.

The blast occurred at 7 p.m. on Wednesday, according to state media. Those injured were taken to hospital. At just after 9:30, the People’s Daily said at least 50 were hurt. No other details were available.

CCTV said assailants attacked crowds with knives and set off the explosions at the same time, Associated Press reported.

Urumqi is the capital of the Xinjiang Uyghur Autonomous Region, which encompasses a vast arid area on the country’s western flank. Its Muslim population has come under heavy scrutiny by Chinese authorities, who have blamed separatists from the region for a March 1 knife attack at another station, at Kunming in the country’s south. Twenty-nine people died in that attack, which served as the worst incidence of terror on Chinese soil. China also blamed Uyghur separatists for a dramatic attack on Tiananmen Square in October, when a car exploded in the symbolic heart of China.

Mr. Xi, who was in Xinjiang until Wednesday morning, had this week vowed a crackdown on terrorism.

China will adopt a “strike-first” policy, he said in comments reported by state media. He called for more tools in the fight against terrorism.

“(We must) make terrorists become like rats scurrying across a street, with everybody shouting ‘beat them!’ ” he said.

Despite state media’s use of Twitter to describe the attack in English, all references to the Urumqi bombing appeared quickly scrubbed from Chinese social media. Chinese-language posts about the attack were hidden within minutes, and posters advised that they had “violated some regulations” in writing about an event that state media itself had first made public.

Any challenges to authority in China, particularly violent ones, are viewed with extreme sensitivity by the state.

Xinjiang has traditionally been dominated by the Uyghur ethnic minority. However, a concerted effort to settle the region with ethnic Chinese has led to sweeping change, and Uyghurs are now minorities in their own home. Beijing wants resources from Xinjiang, which also serves as critical geostrategic gateway connecting China with Central Asian nations, with whom China wants to build a new “silk road” for trade of oil, gas and other goods.

China has argued that its efforts have lifted the economy of the region, and brought about substantial improvements in the standard of living and well-being of its people.

Many Uyghurs, however, have chafed under heavy surveillance that has accompanied the settlement efforts, as Chinese state security seeks to clamp down on what Beijing has seen as a restive population.

China has, Uyghurs have said, interfered with their practice of religion. Job ads in the region have openly discriminated against Uyghurs, and Han Chinese overwhelmingly make up the top ranks of local power structures. Though the region’s formal name hints at a measure of autonomy, in practice it does not exist.

Tensions frequently boil over into violence. The execution of 30 independence activists in 1997 sparked demonstrations, an army crackdown and a bus bombing. Dozens died and hundreds, perhaps as many as 1,600, were subsequently arrested.

Numerous attacks in ensuing years – often accompanied by bloody remonstrations – have taken place, including at least one thwarted attempt to take down a passenger jet using a suicide bomber.

As recently as this January, a dozen people were killed after bombs were set off at a hair salon and market. At the time, Dilxat Raxit, a spokesman for the World Uighur Congress, said: “The forced repression and provocation is the real reason for the confrontation.”

Soon after the January bombings, state media quoted Politburo Standing Committee member Yu Zhengsheng – one of the most powerful men in China – as calling for tighter control of religion, in comments seen as directly related to Xinjiang.

“Religious followers must expand consciousness of the state,the law and citizenship within religious circles so that the faithful naturally conduct religious activities within the bounds of law and policy,” he said.